8-K: Scholar Rock Announces Promising Phase 1 Trial Data for SRK-181 in Advanced Solid Tumors

Scholar Rock presented encouraging Phase 1 trial data for SRK-181 in combination with pembrolizumab, showing anti-tumor activity in multiple cancer types, particularly in patients resistant to anti-PD-(L)1 therapies.

Summary

• Scholar Rock presented new data from its Phase 1 DRAGON trial of SRK-181 combined with pembrolizumab at the ASCO 2024 Annual Meeting.
• The trial included patients with advanced solid tumors who had previously not responded to anti-PD-(L)1 therapies.
• The combination of SRK-181 and pembrolizumab was generally well-tolerated, with most adverse events being manageable.
• The study showed encouraging objective response rates (ORR) in several tumor types, including clear cell renal cell carcinoma (ccRCC), head and neck squamous cell carcinoma (HNSCC), and melanoma (MEL).
• In ccRCC, the ORR was 23.3%, with a median duration of response (mDoR) of 7.7+ months.
• Biomarker analysis revealed that baseline CD8+ T-cell infiltration and elevated regulatory T-cell (Treg) levels in ccRCC patients correlated with higher response rates.
• Specifically, if enrollment was limited to ccRCC patients with CD8+ infiltration, the ORR increased to 40% and mDoR improved to 9.3 months.
• Similarly, if enrollment was limited to ccRCC patients with elevated Treg levels, the ORR increased to 50% and mDoR improved to 9.8 months.
• The data suggests that these biomarkers could be used to identify patients most likely to respond to SRK-181 and anti-PD-(L)1 combination therapy.

Sentiment

Score: 8

Explanation: The document presents very positive clinical trial results with clear evidence of efficacy and a manageable safety profile. The identification of predictive biomarkers further enhances the potential of the therapy. The company is also actively seeking partnerships, which is a positive sign.

Positives

• The study demonstrated encouraging anti-tumor activity in multiple cancer types, particularly in patients resistant to anti-PD-(L)1 therapies.
• SRK-181 in combination with pembrolizumab was generally well-tolerated, with manageable adverse events.
• Biomarker analysis identified potential patient selection strategies for ccRCC, which could significantly improve response rates.
• The combination therapy showed a positive impact on the tumor microenvironment, with increased CD8+ T-cell infiltration and activation.
• The results support further investigation of SRK-181 as a potential treatment option for advanced solid tumors.

Negatives

• One Grade 4 treatment-related adverse event (generalized dermatitis exfoliative) was observed in one patient.
• The most common adverse events were rash, pruritis, fatigue, and diarrhea.
• Some patients experienced serious adverse events, such as pemphigoid.
• No response was observed in the non-small cell lung cancer (NSCLC) cohort.

Risks

• The study is a Phase 1 trial, and further clinical trials are needed to confirm these results.
• The identified biomarkers need to be validated in larger studies to confirm their predictive value.
• The safety profile needs to be monitored in larger patient populations.
• The long-term efficacy and durability of response need to be evaluated.
• There is a risk that future trials may not replicate the positive results observed in this study.

Future Outlook

Scholar Rock is committed to engaging with the FDA in an end of Phase 1 meeting and will continue to evaluate opportunities to partner this program. They plan to further investigate SRK-181 and the identified biomarkers as a potential patient selection strategy.

Management Comments

• Jay Backstrom, M.D., MPH, President and Chief Executive Officer of Scholar Rock, stated that the data shows promising response to treatment with SRK-181 across multiple tumor types.
• He also mentioned that the anti-tumor activity observed in heavily pretreated cancer patients gives them confidence that SRK-181 could be part of a treatment strategy to overcome immune checkpoint inhibitor-associated resistance.
• He noted that the new finding that baseline CD8+ infiltration status and elevated baseline regulatory T-cell levels in ccRCC correspond with the twofold increase in response rate has the potential to inform a patient selection strategy.

Industry Context

This announcement is significant in the context of the growing need for effective treatments for patients with advanced solid tumors who have developed resistance to anti-PD-(L)1 therapies. The identification of biomarkers that can predict response to treatment is a key area of focus in oncology research, and Scholar Rock's findings could have a significant impact on patient care.

Comparison to Industry Standards

• The objective response rates observed in the trial, particularly in ccRCC and melanoma, are competitive with other investigational therapies in similar patient populations.
• The use of biomarkers to predict response is aligned with current trends in precision medicine, where treatments are tailored to individual patient characteristics.
• The safety profile of SRK-181 in combination with pembrolizumab appears to be manageable, which is an important consideration for combination therapies.
• Companies such as Bristol Myers Squibb, Merck, and Roche are also developing therapies targeting similar pathways, but Scholar Rock's approach with SRK-181 is unique in its selectivity for latent TGF1 activation.
• The results are comparable to other checkpoint inhibitor combination therapies, but the biomarker findings could give SRK-181 a competitive advantage.

Stakeholder Impact

• Shareholders may react positively to the promising clinical trial results.
• Patients with advanced solid tumors may benefit from the development of this new treatment option.
• Employees of Scholar Rock may be motivated by the positive progress of the SRK-181 program.
• Potential partners may be interested in collaborating with Scholar Rock on this program.

Next Steps

• Scholar Rock plans to engage with the FDA in an end of Phase 1 meeting.
• They will continue to evaluate opportunities to partner the SRK-181 program.
• Further investigation of SRK-181 and the identified biomarkers is planned.
• Additional clinical trials will likely be conducted to confirm these results.

Key Dates

Keywords

SRK-181, pembrolizumab, TGF1 inhibitor, cancer, immunotherapy, clinical trial, solid tumors, ccRCC, HNSCC, melanoma, biomarkers, CD8+ T-cells, Treg, ASCO